Method for adjusting the gray scale in the reproduction of digitized images and a system for carrying out said method

Claim 3

A method as recited in claim 1 wherein: the mean level and window-width parameters are varied by a succession of elementary control actions, and wherein the control of the value of the mean level parameter as a function of the value of the window-width parameter occurs at the time of each elementary control action.

Claim 4

A method as recited in claim 2 wherein an elementary control action to control the value of the mean level parameter from an old to a new value comprises: adding to or subtracting from the old value of the mean level parameter a quantity which is proportional to that value of the window-width parameter in effect at the time of the elementary control action, where said proportion has a proportionality factor which is constant.

Claim 5

A method as recited in claim 2 wherein an elementary control action to control the value of the window-width parameter from an old value to a new value comprises: deriving said new value as a product of the old value and a predetermined coefficient.

Claim 6

A method as recited in claim 4 wherein said predetermined coefficient is a one of two coefficients depending on whether said new value is larger or smaller than said old value and wherein one of the two coefficients is a reciprocal of another of the coefficients.

Claim 7

A method as recited in claim 1 wherein the mean level parameter is an image gray level and the window-width parameter is gray window width.

Claim 8

A digitized-image processing system comprising a table of equivalence of gray levels or the like, said table being interposed between means for reading an image memory and a digital-to-analog converter, writing means for modifying the contents of said table of equivalence, wherein said system comprises: first determination means for determining a mean gray level, second determination means for determining a gray window width, said system further comprising computing means connected and to controlling said writing means on the basis of a mean gray level and gray window width defined by said first and second determination means, said first and second determination means controlled by respective variation-control means and wherein said first determination means comprises an operator coupled to an output of said second determination means.

Claim 9

A digitized-image processing system comprising a table of equivalence of gray levels or the like, said table being interposed between means for reading an image memory and a digital-to-analog converter, writing means for modifying the contents of said table of equivalence, wherein said system comprises: first determination means for determining a mean gray level, second determination means for determining a gray window width, said system further comprising computing means connected and to controlling said writing means on the basis of a mean gray level and gray window width defined by said first and second determination means, said first and second determination means controlled by respective variation-control means and wherein said first determination means comprises an operator coupled to an output of said second determination means.